Measurement and prediction of propeller blade surface pressure distributions

The work reported in this text describes the development of an advanced method for the aerodynamic testing of model propellers. The technique involves the measurement of the time averaged surface pressure distributions on rotating model propeller blades, thereby giving access to more detailed information than was previously possible. This information may be used both to improve the fundamental understanding of propeller aerodynamics, and to provide high quality detailed validation data for theoretical predictive techniques. The experimental system is described, and results showing the effects of changes in advance ratio, blade setting angle, number of blades and nacelle geometry are discussed. Flow phenomena unrepresentative of full scale flight conditions were identified and removed, thus ensuring the realistic testing of propellers at model scale. In addition, the development of a potential flow theoretical method for the prediction of the flowfield around propeller/axisymmetric nacelle combinations is described. The technique uses a vortex lattice representation for the propeller blades, together with a surface source distribution for the non-lifting surfaces (spinner, hub and nacelle). The method is found to predict all the trends experimentally observed and to give good numerical agreement for the blade surface pressures over the outboard half of the propeller radiu